Our gateways uses the following IP addresses for SIP and RTP/udptl packets:
SIP packets are to be sent to UDP port 5060 or 5080 and inbound calls will come from the UDP port used to register or port 5060 for static registrations.
The following addresses are also used for RTP/udptl packets only:
188.8.131.52/30 (Full Subnet Mask: 255.255.255.252)
184.108.40.206/26 (Full Subnet Mask: 255.255.255.192)
RTP/udptl packets will use a random UDP port in the 16384 to 65000 range. (35000 to 65000 for the SIP gateways from the first list above and 16384 to 32768 for the media gateways from the second list above).
The SIP packets and RTP packets for a single session will often use different IP addresses.